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                <ol class="chapter"><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">1.</strong> 类型系统</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../01_类型系统/Rust_Concept_Clarification_Deref_vs_AsRef_vs_Borrow_vs_Cow/Rust_Concept_Clarification_Deref_vs_AsRef_vs_Borrow_vs_Cow.html"><strong aria-hidden="true">1.1.</strong> Rust Concept Clarification Deref vs AsRef vs Borrow vs Cow</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/Rust_Concept_Clarification_Deref_vs_AsRef_vs_Borrow_vs_Cow/Deref_AsRef_Borrow_Cow释义.html"><strong aria-hidden="true">1.2.</strong> Deref AsRef Borrow Cow 释义</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/Rust的Borrow和AsRef：让你的代码用起来像呼吸一样自然/Rust的Borrow和AsRef：让你的代码用起来像呼吸一样自然.html"><strong aria-hidden="true">1.3.</strong> Rust的Borrow和AsRef：让你的代码用起来像呼吸一样自然</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/Rust的Cow类型有什么用？详解Cow及其用途/Rust的Cow类型有什么用？详解Cow及其用途.html"><strong aria-hidden="true">1.4.</strong> Rust的Cow类型有什么用？详解Cow及其用途</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/判别Fn、FnMut、FnOnce的标准/判别Fn、FnMut、FnOnce的标准.html"><strong aria-hidden="true">1.5.</strong> 判别Fn、FnMut、FnOnce的标准</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/一行代码告诉你内部可变性的真相(UnsafeCell)/一行代码告诉你内部可变性的真相(UnsafeCell).html"><strong aria-hidden="true">1.6.</strong> 一行代码告诉你内部可变性的真相(UnsafeCell)</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/Tour_of_Rust's_Standard_Library_Traits/Tour_of_Rust's_Standard_Library_Traits.html"><strong aria-hidden="true">1.7.</strong> Tour of Rust's Standard Library Traits</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/逆变、协变与子类型，以及Rust/逆变、协变与子类型，以及Rust.html"><strong aria-hidden="true">1.8.</strong> 逆变、协变与子类型，以及Rust</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/Rust自引用结构、Pin与Unpin/Rust自引用结构、Pin与Unpin.html"><strong aria-hidden="true">1.9.</strong> Rust自引用结构、Pin与Unpin</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/为什么Rust需要Pin,Unpin/为什么Rust需要Pin,Unpin.html"><strong aria-hidden="true">1.10.</strong> 译：为什么 Rust 需要 Pin, Unpin ？</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/定海神针Pin和Unpin/定海神针Pin和Unpin.html"><strong aria-hidden="true">1.11.</strong> 译：定海神针 Pin 和 Unpin</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/sizedness-in-rust/sizedness-in-rust.html"><strong aria-hidden="true">1.12.</strong> Sizedness in Rust</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/Rust生命周期集大成者PhantomData〈T〉/Rust生命周期集大成者PhantomData〈T〉.html"><strong aria-hidden="true">1.13.</strong> Rust生命周期集大成者 PhantomData&lt;T&gt;</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/数据库表达式执行的黑魔法：用Rust做类型体操/数据库表达式执行的黑魔法：用Rust做类型体操_Part_0.html"><strong aria-hidden="true">1.14.</strong> 数据库表达式执行的黑魔法：用Rust做类型体操 Part 0</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/数据库表达式执行的黑魔法：用Rust做类型体操/数据库表达式执行的黑魔法：GAT实现引用类型关联_Part_1.html"><strong aria-hidden="true">1.15.</strong> 数据库表达式执行的黑魔法：GAT实现引用类型关联 Part 1</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/数据库表达式执行的黑魔法：用Rust做类型体操/数据库表达式执行的黑魔法：用HRTB写bound_Part_2.html"><strong aria-hidden="true">1.16.</strong> 数据库表达式执行的黑魔法：用HRTB写bound Part 2</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/数据库表达式执行的黑魔法：用Rust做类型体操/数据库表达式执行的黑魔法：用Rust做类型体操之用宏展开重复代码_Part_3_&_4.html"><strong aria-hidden="true">1.17.</strong> 数据库表达式执行的黑魔法：用Rust做类型体操之用宏展开重复代码 Part 3 & 4</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/数据库表达式执行的黑魔法：用Rust做类型体操/数据库表达式执行的黑魔法：与Rust编译器斗智斗勇之表达式向量化_Part_5_&_6.html"><strong aria-hidden="true">1.18.</strong> 数据库表达式执行的黑魔法：与Rust编译器斗智斗勇之表达式向量化 Part 5 & 6</a></li><li class="chapter-item expanded "><a href="../../01_类型系统/数据库表达式执行的黑魔法：用Rust做类型体操/数据库表达式执行的黑魔法：在Rust中用宏关联逻辑类型和实际类型_Part_7.html"><strong aria-hidden="true">1.19.</strong> 数据库表达式执行的黑魔法：在Rust中用宏关联逻辑类型和实际类型 Part 7</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">2.</strong> 生命周期</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../02_生命周期/Rust中的生命周期——从StrSplit实例说开去/Rust中的生命周期——从StrSplit实例说开去.html"><strong aria-hidden="true">2.1.</strong> Rust中的生命周期——从StrSplit实例说开去</a></li><li class="chapter-item expanded "><a href="../../02_生命周期/与ChatGPT深度对话来学Rust生命周期/与ChatGPT深度对话来学Rust生命周期.html"><strong aria-hidden="true">2.2.</strong> 与ChatGPT深度对话来学Rust生命周期</a></li><li class="chapter-item expanded "><a href="../../02_生命周期/进击的Rust生命周期——early_bound与late_bound（1）/进击的Rust生命周期——early_bound与late_bound（1）.html"><strong aria-hidden="true">2.3.</strong> 进击的Rust生命周期——early_bound与late_bound（1）</a></li><li class="chapter-item expanded "><a href="../../02_生命周期/进击的Rust生命周期——early_bound与late_bound（2）/进击的Rust生命周期——early_bound与late_bound（2）.html"><strong aria-hidden="true">2.4.</strong> 进击的Rust生命周期——early_bound与late_bound（2）</a></li><li class="chapter-item expanded "><a href="../../02_生命周期/进击的Rust生命周期——一力降十会的MIR（1）/进击的Rust生命周期——一力降十会的MIR（1）.html"><strong aria-hidden="true">2.5.</strong> 进击的Rust生命周期——一力降十会的MIR（1）</a></li><li class="chapter-item expanded "><a href="../../02_生命周期/进击的Rust生命周期——一力降十会的MIR（2）/进击的Rust生命周期——一力降十会的MIR（2）.html"><strong aria-hidden="true">2.6.</strong> 进击的Rust生命周期——一力降十会的MIR（2）</a></li><li class="chapter-item expanded "><a href="../../02_生命周期/Common_Rust_Lifetime_Misconceptions/Common_Rust_Lifetime_Misconceptions.html"><strong aria-hidden="true">2.7.</strong> Common Rust Lifetime Misconceptions</a></li><li class="chapter-item expanded "><a href="../../02_生命周期/Rust生命周期常见误区/Rust生命周期常见误区.html"><strong aria-hidden="true">2.8.</strong> 译：Rust生命周期常见误区</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">3.</strong> 无畏并发</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../05_无畏并发/简单写个Rust无锁队列/简单写个Rust无锁队列.html"><strong aria-hidden="true">3.1.</strong> 简单写个Rust无锁队列</a></li><li class="chapter-item expanded "><a href="../../05_无畏并发/进击的Rust多线程——混合自旋锁/进击的Rust多线程——混合自旋锁.html"><strong aria-hidden="true">3.2.</strong> 进击的Rust多线程——混合自旋锁</a></li><li class="chapter-item expanded "><a href="../../05_无畏并发/An_unsafe_tour_of_Rust's_Send_and_Sync/An_unsafe_tour_of_Rust's_Send_and_Sync.html"><strong aria-hidden="true">3.3.</strong> An unsafe tour of Rust's Send and Sync</a></li><li class="chapter-item expanded "><a href="../../05_无畏并发/进击的Rust多线程——Send与Sync/进击的Rust多线程——Send与Sync.html"><strong aria-hidden="true">3.4.</strong> 进击的Rust多线程——Send与Sync</a></li><li class="chapter-item expanded "><a href="../../05_无畏并发/进击的Rust多线程——离经叛道的PhantomData/进击的Rust多线程——离经叛道的PhantomData.html"><strong aria-hidden="true">3.5.</strong> 进击的Rust多线程——离经叛道的PhantomData</a></li><li class="chapter-item expanded "><a href="../../05_无畏并发/Rust_Async_Pin概念解析/Rust_Async_Pin概念解析.html"><strong aria-hidden="true">3.6.</strong> Rust Async: Pin概念解析</a></li><li class="chapter-item expanded "><a href="../../05_无畏并发/Rust和C++的并发库对比/Rust和C++的并发库对比.html"><strong aria-hidden="true">3.7.</strong> 译：Rust 和 C++ 的并发库对比</a></li><li class="chapter-item expanded "><a href="../../05_无畏并发/Rust原子类型和内存排序/Rust原子类型和内存排序.html"><strong aria-hidden="true">3.8.</strong> Rust原子类型和内存排序</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">4.</strong> 网络编程</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../06_网络编程/从编解码层面理解WebSocket_手写一个WebSocket/从编解码层面理解WebSocket_手写一个WebSocket.html"><strong aria-hidden="true">4.1.</strong> 从编解码层面理解WebSocket 手写一 个WebSocket</a></li><li class="chapter-item expanded "><a href="../../06_网络编程/透过Rust探索系统的本原：网络篇/透过Rust探索系统的本原：网络篇.html"><strong aria-hidden="true">4.2.</strong> 透过Rust探索系统的本原：网络篇</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">5.</strong> 轮子系列</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../07_轮子系列/700行Rust写一个内存分配器/700行Rust写一个内存分配器.html"><strong aria-hidden="true">5.1.</strong> 700行Rust写一个内存分配器</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/Rust：网络库的实现思路/Rust：网络库的实现思路.html"><strong aria-hidden="true">5.2.</strong> Rust：网络库的实现思路</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/Rust异步运行时基础部件/Rust异步运行时基础部件.html"><strong aria-hidden="true">5.3.</strong> Rust异步运行时基础部件</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/使用Rust+epoll编写异步IO框架/使用Rust+epoll编写异步IO框架（1）.html"><strong aria-hidden="true">5.4.</strong> 使用Rust+epoll编写异步IO框架（1）</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/使用Rust+epoll编写异步IO框架/使用Rust+epoll编写异步IO框架（2）.html"><strong aria-hidden="true">5.5.</strong> 使用Rust+epoll编写异步IO框架（2）</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/使用Rust+epoll编写异步IO框架/使用Rust+epoll编写异步IO框架（3）.html"><strong aria-hidden="true">5.6.</strong> 使用Rust+epoll编写异步IO框架（3）</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/用rust从零开发一套web框架/用rust从零开发一套web框架：day1.html"><strong aria-hidden="true">5.7.</strong> 用rust从零开发一套web框架：day1</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/用rust从零开发一套web框架/用rust从零开发一套web框架：day2.html"><strong aria-hidden="true">5.8.</strong> 用rust从零开发一套web框架：day2</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/用rust从零开发一套web框架/用rust从零开发一套web框架：day3.html"><strong aria-hidden="true">5.9.</strong> 用rust从零开发一套web框架：day3</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/用rust从零开发一套web框架/用rust从零开发一套web框架：day4.html"><strong aria-hidden="true">5.10.</strong> 用rust从零开发一套web框架：day4</a></li><li class="chapter-item expanded "><a href="../../07_轮子系列/用rust从零开发一套web框架/用rust从零开发一套web框架：day5.html" class="active"><strong aria-hidden="true">5.11.</strong> 用rust从零开发一套web框架：day5</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">6.</strong> 奇技淫巧</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../08_奇技淫巧/Copy-On-Write是不是优化？/Copy-On-Write是不是优化？.html"><strong aria-hidden="true">6.1.</strong> 译：Copy-On-Write是不是优化？</a></li><li class="chapter-item expanded "><a href="../../08_奇技淫巧/揭秘神奇的Rust_Axum风格的函数实现/揭秘神奇的Rust_Axum风格的函数实现.html"><strong aria-hidden="true">6.2.</strong> 译：揭秘神奇的 Rust Axum 风格的函数实现</a></li><li class="chapter-item expanded "><a href="../../08_奇技淫巧/“变长参数”函数与回调/“变长参数”函数与回调.html"><strong aria-hidden="true">6.3.</strong> “变长参数”函数与回调</a></li><li class="chapter-item expanded "><a href="../../08_奇技淫巧/Rust字符串格式化的幕后：format_args!()/Rust字符串格式化的幕后：format_args!().html"><strong aria-hidden="true">6.4.</strong> 译：Rust字符串格式化的幕后：format_args!()</a></li><li class="chapter-item expanded "><a href="../../08_奇技淫巧/给Rust带来一点C++特产/给Rust带来一点C++特产.html"><strong aria-hidden="true">6.5.</strong> 给Rust带来一点C++特产</a></li><li class="chapter-item expanded "><a href="../../08_奇技淫巧/一步步实现_Rust_Bevy_ECS_的_System_简化版本/一步步实现_Rust_Bevy_ECS_的_System_简化版本.html"><strong aria-hidden="true">6.6.</strong> 一步步实现 Rust Bevy ECS 的 System 简化版本</a></li><li class="chapter-item expanded "><a href="../../08_奇技淫巧/Exploring_Design_Patterns_in_Rust_with_Algorithmic_Trading_Examples/Exploring_Design_Patterns_in_Rust_with_Algorithmic_Trading_Examples.html"><strong aria-hidden="true">6.7.</strong> Exploring Design Patterns in Rust with Algorithmic Trading Examples</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">7.</strong> 源码分析</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../09_源码分析/Rust并发：bytes源码分析/Rust并发：bytes源码分析.html"><strong aria-hidden="true">7.1.</strong> Rust并发：bytes源码分析</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Rust并发：标准库Arc源码分析/Rust并发：标准库Arc源码分析.html"><strong aria-hidden="true">7.2.</strong> Rust并发：标准库Arc源码分析</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Rust并发：标准库sync_Once源码分析/Rust并发：标准库sync_Once源码分析.html"><strong aria-hidden="true">7.3.</strong> Rust并发：标准库sync::Once源码分析</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Rust源码阅读：引用计数Rc/Rust源码阅读：引用计数Rc.html"><strong aria-hidden="true">7.4.</strong> Rust源码阅读：引用计数Rc</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Rust源码阅读：Cell、RefCell与内部可变性/Rust源码阅读：Cell、RefCell与内部可变性.html"><strong aria-hidden="true">7.5.</strong> Rust源码阅读： Cell、RefCell与内部可变性</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/关于_Rust_的_UnsafeCell、Cell_与_RefCell/关于_Rust_的_UnsafeCell、Cell_与_RefCell.html"><strong aria-hidden="true">7.6.</strong> 关于 Rust 的 UnsafeCell、Cell 与 RefCell</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Rust_Async_async-stream源码分析/Rust_Async_async-stream源码分析.html"><strong aria-hidden="true">7.7.</strong> Rust Async: async-stream源码分析</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/走进Tokio的异步世界/走进Tokio的异步世界.html"><strong aria-hidden="true">7.8.</strong> 走进 Tokio 的异步世界</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/tokio.rs_runtime的实现/tokio.rs_runtime的实现.html"><strong aria-hidden="true">7.9.</strong> tokio.rs runtime 的实现</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Tokio_internals/Tokio_internals.html"><strong aria-hidden="true">7.10.</strong> Tokio internals</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Tokio_internals/译文：Tokio內部机制.html"><strong aria-hidden="true">7.11.</strong> 译：Tokio 内部机制</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Rust_Axum_HTTP_框架的架构分析/Rust_Axum_HTTP_框架的架构分析.html"><strong aria-hidden="true">7.12.</strong> Rust Axum HTTP 框架的架构分析</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/安利一个Rust_Game_Engine：Bevy--ECS部分/安利一个Rust_Game_Engine：Bevy--ECS部分.html"><strong aria-hidden="true">7.13.</strong> 安利一个Rust Game Engine：Bevy--ECS部分</a></li><li class="chapter-item expanded "><a href="../../09_源码分析/Tokio_解析之任务调度/Tokio_解析之任务调度.html"><strong aria-hidden="true">7.14.</strong> Tokio 解析之任务调度</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">8.</strong> 生态观察</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../11_生态观察/Rust_web_frameworks_have_subpar_error_reporting/Rust_web_frameworks_have_subpar_error_reporting.html"><strong aria-hidden="true">8.1.</strong> Rust web frameworks have subpar error reporting</a></li><li class="chapter-item expanded "><a href="../../11_生态观察/SeaORM：要做Rust版本的ActiveRecord/SeaORM：要做Rust版本的ActiveRecord.html"><strong aria-hidden="true">8.2.</strong> SeaORM：要做Rust版本的ActiveRecord</a></li></ol></li><li class="chapter-item expanded "><a href="../../empty.html"><strong aria-hidden="true">9.</strong> 死灵终极</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../12_死灵终极/Learn_Rust_the_Dangerous_Way_系列文章翻译/Learn_Rust_the_Dangerous_Way_系列文章翻译_总述.html"><strong aria-hidden="true">9.1.</strong> 译：Learn Rust the Dangerous Way 总述</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Learn_Rust_the_Dangerous_Way_系列文章翻译/Learn_Rust_the_Dangerous_Way_系列文章翻译_0.html"><strong aria-hidden="true">9.2.</strong> 译：Learn Rust the Dangerous Way 0</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Learn_Rust_the_Dangerous_Way_系列文章翻译/Learn_Rust_the_Dangerous_Way_系列文章翻译_1.html"><strong aria-hidden="true">9.3.</strong> 译：Learn Rust the Dangerous Way 1</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Learn_Rust_the_Dangerous_Way_系列文章翻译/Learn_Rust_the_Dangerous_Way_系列文章翻译_2.html"><strong aria-hidden="true">9.4.</strong> 译：Learn Rust the Dangerous Way 2</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Learn_Rust_the_Dangerous_Way_系列文章翻译/Learn_Rust_the_Dangerous_Way_系列文章翻译_3.html"><strong aria-hidden="true">9.5.</strong> 译：Learn Rust the Dangerous Way 3</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Learn_Rust_the_Dangerous_Way_系列文章翻译/Learn_Rust_the_Dangerous_Way_系列文章翻译_4.html"><strong aria-hidden="true">9.6.</strong> 译：Learn Rust the Dangerous Way 4</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Learn_Rust_the_Dangerous_Way_系列文章翻译/Learn_Rust_the_Dangerous_Way_系列文章翻译_5.html"><strong aria-hidden="true">9.7.</strong> 译：Learn Rust the Dangerous Way 5</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Unsafe_Rust_随堂小测/Unsafe_Rust_随堂小测（一）.html"><strong aria-hidden="true">9.8.</strong> Unsafe Rust 随堂小测（一）</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Unsafe_Rust_随堂小测/Unsafe_Rust_随堂小测（二）.html"><strong aria-hidden="true">9.9.</strong> Unsafe Rust 随堂小测（二）</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Unsafe_Rust_随堂小测/Unsafe_Rust_随堂小测（三）.html"><strong aria-hidden="true">9.10.</strong> Unsafe Rust 随堂小测（三）</a></li><li class="chapter-item expanded "><a href="../../12_死灵终极/Unsafe_Rust_随堂小测/Unsafe_Rust_随堂小测参考答案.html"><strong aria-hidden="true">9.11.</strong> Unsafe Rust 随堂小测参考答案</a></li></ol></li></ol>
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                        <h1 id="用-rust-从零开发一套-web-框架day5"><a class="header" href="#用-rust-从零开发一套-web-框架day5">用 rust 从零开发一套 web 框架：day5</a></h1>
<p><a href="https://juejin.cn/user/677714513628055/posts">linken_coding</a></p>
<p>2022-12-073,574阅读6分钟</p>
<p>专栏： </p>
<p>rust从零开发轮子系列</p>
<p>开启掘金成长之旅！这是我参与「掘金日新计划 · 12 月更文挑战」的第9天，<a href="https://juejin.cn/post/7167294154827890702">点击查看活动详情</a></p>
<h2 id="肉身化神"><a class="header" href="#肉身化神">肉身化神</a></h2>
<p>到了现在这一步，想必大家应该也能猜到要干啥了。没错！中间件，它来了！只要完成中间件的插入和处理，那整个框架的灵魂也就完整了。</p>
<h3 id="中间件是什么"><a class="header" href="#中间件是什么">中间件是什么</a></h3>
<p>中间件(middlewares)，简单说，就是非业务的技术类组件。Web 框架本身不可能去理解所有的业务，因而不可能实现所有的功能。因此，框架需要有一个插口，允许用户自己定义功能，嵌入到框架中，仿佛这个功能是框架原生支持的一样。因此，对中间件而言，需要考虑 2 个比较关键的点：</p>
<ol>
<li>插入点在哪？使用框架的人并不关心底层逻辑的具体实现，如果插入点太底层，中间件逻辑就会非常复杂。如果插入点离用户太近，那和用户直接定义一组函数，每次在 <code>Handler</code> 中手工调用没有多大的优势了。</li>
<li>中间件的输入是什么？中间件的输入，决定了扩展能力。暴露的参数太少，用户发挥空间有限。</li>
</ol>
<p>那对于我们这个 Web 框架而言，中间件应该设计成什么样呢？接下来的内容，基本上是我根据路由节点数据结构来实现的。</p>
<h3 id="中间件的位置"><a class="header" href="#中间件的位置">中间件的位置</a></h3>
<p>先回忆下在前面的路由节点树里，我们其实预留了用来存放中间件的 <code>hooks</code> 数组。</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>//Trie 树
#[derive(Clone)]
pub struct RouterNode {
    pub pattern: Option&lt;String&gt;,   // 待匹配路由，例如 /p/:lang
    pub part: Option&lt;String&gt;,      // 路由中的一部分，例如 :lang
    pub children: Vec&lt;RouterNode&gt;, // 子节点，例如 [doc, tutorial, intro]
    pub is_match: bool,            // 是否精确匹配，part 含有 : 或 * 时为true
    pub hooks: Vec&lt;String&gt;,  //中间件钩子函数
    pub method: Option&lt;String&gt;,    //请求方法
}
<span class="boring">}
</span></code></pre></pre>
<p>只要把<code>hooks</code>的内容替换为<code>Handler</code>即可（怎么还多了个<code>Arc</code>,跟说好的不一样啊?有兴趣的同学可以自己思考一下）：</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub hooks: Vec&lt;Arc&lt;Handler&gt;&gt;
<span class="boring">}
</span></code></pre></pre>
<p>比如作用于全局的中间件，即所有的请求都会被中间件处理。那只要在顶层的 <code>hooks</code> 加上这个中间件就可以了。如果是作用在分组的中间件，同样可以在该分组的主节点 <code>hooks</code> 加上。甚至单个路由可以在自己的 <code>hooks</code> 加上属于自己的中间件。</p>
<h3 id="中间件设计"><a class="header" href="#中间件设计">中间件设计</a></h3>
<p>我们这里中间件的定义与路由映射的 <code>Handler</code> 一致，处理的输入是<code>AppContext</code>对象。插入点是框架接收到请求初始化<code>AppContext</code>对象后，允许用户使用自己定义的中间件做一些额外的处理，例如记录日志等，以及对<code>AppContext</code>进行二次加工。不过，我们这里先实现简单的前置中间件，在路由 <code>Handler</code>之前进行处理。后面有时间再继续优化。</p>
<p>那我们的中间件要怎么样加到路由节点树上面呢,先来看下面的示例：</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let mut router = Router::new()
        .hooks(global_hook)
        .get(&quot;/user&quot;, handle_hello)
        .get(&quot;/ghost/:id&quot;, handle_hello);

let g1 = router.group(&quot;/admin&quot;).hooks(group_hook);

g1.get(&quot;/hello&quot;, |c: &amp;mut AppContext| {
        let s = format!(&quot;hello world from admin&quot;);
        c.string(None, &amp;s)
    });
<span class="boring">}
</span></code></pre></pre>
<p>为了让中间件的添加变得简单，我们分别在根<code>Router</code>、路由分组<code>RouterGroup</code>加上<code>hooks</code>方法。但是，其本质都在调用<code>RouterNode</code>的<code>add_hooks</code></p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>impl Router{
  ...
  //新增中间件钩子函数
    pub fn hooks&lt;F&gt;(mut self, handler: F) -&gt; Self
    where
        F: Fn(&amp;mut AppContext) + Send + Sync + 'static,
    {
        self.roots.hooks.push(Arc::new(handler));
        self
    }

    //新增中间件钩子函数
    pub fn add_hooks&lt;F&gt;(&amp;mut self, path: &amp;str, method: Option&lt;&amp;str&gt;, handler: F)
    where
        F: Fn(&amp;mut AppContext) + Send + Sync + 'static,
    {
        let method = match method {
            Some(method) =&gt; Some(method.to_string()),
            None =&gt; None,
        };

        if let Some(node) = self.roots.match_path_mut(path, method, true) {
            node.add_hooks(handler);
        } else {
            let parts = parse_pattern(path);
            let mut child = self.roots.new_child(parts[0]);
            child.add_hooks(handler);
            self.roots.children.push(child)
        }
    }
}

impl RouterNode{
  ...
  //新增中间件钩子函数
    pub fn add_hooks&lt;F&gt;(&amp;mut self, handler: F)
    where
        F: Fn(&amp;mut AppContext) + Send + Sync + 'static,
    {
        self.hooks.push(Arc::new(handler));
    }
}

impl&lt;'a&gt; RouterGroup&lt;'a&gt; {
  ...
  //新增中间件钩子函数
    pub fn hooks&lt;F&gt;(self, handler: F) -&gt; Self
    where
        F: Fn(&amp;mut AppContext) + Send + Sync + 'static,
    {
        self.router.add_hooks(&amp;self.path, None, handler);
        self
    }
}
<span class="boring">}
</span></code></pre></pre>
<p>可能细心的同学会发现：你这个不过是在全局和分组上面添加中间件，那我怎么在单个路由添加中间件啊。</p>
<p>哎，这位同学是有些细心，但还不够细心。我直接调用<code>Router</code>的<code>add_hooks</code>函数，只要传入相应的路由和<code>handler</code>，不就添加上了单个路由的中间件了。</p>
<p>当然，中间件这么简单就添加上去了，似乎也太儿戏了。（没办法，个人能力有限，暂时也没有更好的处理办法了，后面有时间再琢磨琢磨，也欢迎大家来讨论完善）</p>
<h3 id="优雅关机"><a class="header" href="#优雅关机">优雅关机</a></h3>
<p>现在，我们这个web框架的基本架构已经完成了。虽然非常简陋，也不是不能用。我们继续来优化一下，逐步丰富一下细节部分，比如加上<code>CTRL+C</code>关机。</p>
<p>其实<code>hyper</code>和<code>tokio</code>自身是带有关机服务的，我们的框架是基于<code>hyper</code>和<code>tokio</code>，自然也是调用他们的方法：</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub async fn run(addr: SocketAddr, router: Router) {
    ...
    let server = Server::bind(&amp;addr).serve(make_service_fn);

    let graceful = server.with_graceful_shutdown(shutdown_signal());

    // Await the `server` receiving the signal...
    if let Err(e) = graceful.await {
        eprintln!(&quot;server error: {}&quot;, e);
    }
}

//CTRL+C关机
async fn shutdown_signal() {
    tokio::signal::ctrl_c().await.expect(&quot;CTRL+C 关机失败&quot;);
}
<span class="boring">}
</span></code></pre></pre>
<h3 id="日志记录"><a class="header" href="#日志记录">日志记录</a></h3>
<p>我们再加上日志记录和一些debug信息，这样整个路由链路追踪起来也更方便些。</p>
<p>当然,为了方便<code>debug</code>，我们先在<code>Router</code>和路由节点树<code>RouterNode</code>实现<code>Debug</code>特征：</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use std::fmt::Debug;

impl Debug for Router {
    fn fmt(&amp;self, f: &amp;mut std::fmt::Formatter&lt;'_&gt;) -&gt; std::fmt::Result {
        f.debug_struct(&quot;Router&quot;).field(&quot;roots&quot;, &amp;self.roots).finish()
    }
}

impl Debug for RouterNode {
    fn fmt(&amp;self, f: &amp;mut std::fmt::Formatter&lt;'_&gt;) -&gt; std::fmt::Result {
        f.debug_struct(&quot;RouterNode&quot;)
            .field(&quot;pattern&quot;, &amp;self.pattern)
            .field(&quot;part&quot;, &amp;self.part)
            .field(&quot;children&quot;, &amp;self.children)
            .field(&quot;is_match&quot;, &amp;self.is_match)
            .field(&quot;method&quot;, &amp;self.method)
            .finish()
    }
}
<span class="boring">}
</span></code></pre></pre>
<p>在<code>Cargo.toml</code>增加<code>log</code>日志库:</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>[dependencies]
...
log = &quot;0.4.17&quot;

[dev-dependencies]
env_logger = &quot;0.9.3&quot;

[[example]]
name = &quot;hello&quot;
path = &quot;examples/hello.rs&quot;
<span class="boring">}
</span></code></pre></pre>
<p>注意：<code>env_logger</code>这个库是在<code>dev-dependencies</code>环境。这里的依赖只会在运行测试、示例和 benchmark 时才会被引入。</p>
<p>另外，在各处函数埋下记录点位：</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>async fn handler(addr: SocketAddr, req: Request&lt;Body&gt;, router: Arc&lt;Router&gt;) -&gt; Result&lt;Response&lt;Body&gt;, Infallible&gt; {
  
    //获取节点
    let (node, params) = router.get_route(req.method().clone().into(), req.uri().path());
    debug!(&quot;当前路由节点：{:#?}&quot;, node);
    if let Some(node) = node {
        ...
        debug!(&quot;当前路由AppContext：{:#?}&quot;, context);
        let mut hooks = Vec::new();
        (handle)(&amp;mut context);
    } else {
        context.string(Some(StatusCode::NOT_FOUND), &quot;404 not found&quot;);
    }
    Ok(context.response)
}

pub async fn run(addr: SocketAddr, router: Router) {
    ...
    debug!(&quot;路由表：{:#?}&quot;, router.clone());

    ...
    let graceful = server.with_graceful_shutdown(shutdown_signal());
    info!(&quot;启动成功，启动端口为: {}&quot;, addr);
    ...
}

async fn shutdown_signal() {
    tokio::signal::ctrl_c().await.expect(&quot;CTRL+C 关机失败&quot;);
    info!(&quot;收到ctrl+c关机服务&quot;);
}

//获取路由节点
pub fn get_route(&amp;self, method: Method, path: &amp;str) -&gt; (Option&lt;&amp;RouterNode&gt;, HashMap&lt;String, String&gt;) {
    trace!(&quot;查找路由:{}&quot;, path);
    let search_parts = parse_pattern(path);
    ...
    trace!(&quot;路径中的参数值：{:?}&quot;, params);
    return (n, params);
}


//插入节点
pub fn insert(&amp;mut self, method: Method, path: &amp;str, parts: Vec&lt;&amp;str&gt;, height: usize) {
    if parts.len() == height {
        self.pattern = Some(String::from(path));
        self.method = Some(String::from(method.as_str()));
        trace!(&quot;插入节点：{:#?}&quot;,self);
        return;
    }
    ...
}
<span class="boring">}
</span></code></pre></pre>
<p>刚好也可以梳理一下现在的文件目录，将<code>RouterGroup</code>、<code>RouterNode</code>和<code>Router</code>以及<code>AppContext</code>拆分出来提取到单个文件，而之前用来测试的<code>main</code>函数,也可提取到<code>examples/hello.rs</code>，作为独立的测试文件。现在，整个框架的目录应该如下：</p>
<p><img src="https://p1-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/1f9d54068a5649069819b5cd05752e0f~tplv-k3u1fbpfcp-zoom-in-crop-mark:1512:0:0:0.awebp?" alt="1670315859843.png" /></p>
<p>在<code>main</code>函数中初始化<code>env_logger</code>日志库，加上几个测试的路由：</p>
<pre><pre class="playground"><code class="language-rust">use env_logger::{self, Env};
use ray::{context::AppContext, router::Router, server};
use std::net::SocketAddr;

#[tokio::main]

async fn main() {
    let env = Env::default()
        .filter_or(&quot;MY_LOG_LEVEL&quot;, &quot;debug&quot;)//这里修改日志等级
        .write_style_or(&quot;MY_LOG_STYLE&quot;, &quot;always&quot;);

    env_logger::init_from_env(env);

    let handle_hello = |c: &amp;mut AppContext| c.string(None, &quot;hello world from handler&quot;);

    let get_hello = |c: &amp;mut AppContext| {
        let key = format!(&quot;hello world from post,query: {}&quot;, c.params.get(&quot;id&quot;).unwrap());
        return c.string(None, &amp;key);
    };

    let post_hello = |c: &amp;mut AppContext| {
        let key = format!(&quot;hello world from post,query&quot;);
        return c.string(None, &amp;key);
    };

    let global_hook = |c: &amp;mut AppContext| println!(&quot;Hello from global_hook,path: {:?}&quot;, c.path);
    let group_hook = |c: &amp;mut AppContext| println!(&quot;Hello from group_hook,path: {:?}&quot;, c.path);
    let handle_hook = |c: &amp;mut AppContext| println!(&quot;Hello from handle_hook,path: {:?}&quot;, c.path);
 
    let mut router = Router::new()
        .hooks(global_hook)
        .get(&quot;/user&quot;, handle_hello)
        .get(&quot;/user/index&quot;, handle_hello)
        .get(&quot;/ghost/:id&quot;, get_hello)

    router.add_hooks(&quot;/user/index&quot;,Some(&quot;get&quot;), handle_hook);
    
    let g1 = router.group(&quot;/admin&quot;).hooks(group_hook);

    g1.get(&quot;/hello&quot;, |c: &amp;mut AppContext| {
        let s = format!(&quot;hello world from admin&quot;);
        c.string(None, &amp;s)
    })
    .get(&quot;/index&quot;, |c: &amp;mut AppContext| {
        let s = format!(&quot;hello world from index&quot;);
        c.string(None, &amp;s)
    });
    // Run the server like above...
    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));

    server::run(addr, router).await;
}
</code></pre></pre>
<p>最后，运行一下测试文件，应该可以看到不少日志信息：</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>cargo run --example hello
<span class="boring">}
</span></code></pre></pre>

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